If the house was built in the 80's I can almost guarantee you it is just concrete underneath. I would look at ripping it up and replacing with the wood, cork or bamboo. Laminate is also inexpensive, but really look at what you're getting. Polished concrete floors have a wonderful look to them. All hard surface floors make a house look larger. Take a look at this site with some great - and green - flooring alternatives.
http://www.flooringalternatives.com/content.asp?pid=10\